The present invention relates to a crankshaft of a ferro-metallic material for reciprocating piston engines, preferably internal combustion engines with bearing pins extending in a crankshaft longitudinal center axis and with crank pins offset with respect thereto, whereby the crank pins are delimited by webs extending transversely to the crankshaft longitudinal center axis.
The requirement is made of modern internal combustion engines of the reciprocating piston type construction for passenger motor vehicles, for two-wheeled vehicles or the like, that they be optimized as regards weight and structural space. With a given number of the cylinders and a fixed cylinder diameter, this can be influenced by the cylinder spacings and the crankshaft design.
It is the object of the present invention to provide a crankshaft made from a ferro-metallic material whose weight and structural length is relatively small combined with good mass balancing.
The underlying problems are solved according to the present invention in that the crank pins are provided with relief bores extending in the direction of their center axes, preferably with hollow bores, and in that the counterweights are provided with heavy metal bodies.
The principal advantages achieved with the present invention reside in that the crankshaft is optimized as regards weight and structural length by the bores in the crank pins and the heavy metal bodies in the counterweights. The webs and counterweights can be kept narrow by the heavy metal bodies and the length of the counterweights can be reduced as viewed from the crankshaft longitudinal axis. A particularly favorable construction is contemplated in which the hollow bores extend eccentrically to the crank pins and in which each counterweight includes several heavy metal bodies. The heavy metal bodies with cylindrical shape can be inserted in a simple manner into bores of the counterweights and can be secured thereat.
It is contemplated that the heavy metal bodies are formed by a mass part and a steel jacket surrounding the same and are retained form-lockingly and/or force-lockingly in the bores of the counterweights, which provides a simple assembly and safe retention of the heavy metal bodies.
These and other objects, features and advantages of the present invention will become more apparent from the following description when taken in connection with the accompanying drawing which shows, for purposes of illustration only, several embodiments in accordance with the present invention.